Pre-filter is a must , and 2 be honest you can even puddle jump using a pod filter , if you are crossing creeks though , you should have a sealed airbox and be using the stock air snorkel . if the water level is above your seat , consider another route , OR do what my buddy did with his 400ex and tie 2 big inner tubes to it and float the bastard across!!! It took me an hour to get around that dam creek and he was sitting on the other side just laughing his ass off , needless to say on the way back the blasty got the pontoon treatment as well